Aluminum alloy



United States Patent 3,379,518 ALUMINUM ALLOY Frederick John Kranich,Chicago, 111., assignor to Alumalloy Company, Chicago, 111., apartnership N0 Drawing. Filed Mar. 8, 1966, Ser. No. 532,596 4 Claims.(Cl. 75-142) This invention relates to aluminum alloys and concerns aparticular aluminum alloy suitable for foundry Work and having several1ong-sought advantages heretofore unavailable in a light-metal castingmaterial.

The main objects of this invention is to provide an improved aluminumalloy capable of better sand and permanent mold castings for the foundryindustry, which castings will be dimensionally stable after a shortperiod of natural aging and will have a relatively high density.

It is another object of this invention to provide an aluminum castingalloy which has a high wear resistance under severe conditions ofabrasion and also has high resistance to both acid and alkali corrosion;and to provide such an aluminum alloy that is free machining and whichwill not distort under cold or heat.

In the attainment of an aluminum alloy having these characteristics Ihave found a combination of elemental constituents that appears to becritical in so far as identity is concerned if the maximum advantage ofeach desired characteristic is to be had. I have also found that thebasic material must be substantially pure virgin aluminum, 99.6% pure,and that the proportions of alloying ingredients for a melt of any sizemust be carefully maintained for the best practical results. Commercialaluminum should not be used since its inherent impurities will cause aloss of much of the before-mentioned desired characteristics.

According to my invention, for casting purposes, my improved aluminumalloy consists of the following materials, within the ranges stated, fora batch or melt of predetermined size:

Percent by weight The ranges stated for these ingredients of my improvedaluminum alloy appear to be critical for maximum results and it shouldbe noted that in any case 99.6% pure virgin aluminum should be used. Oldaluminum or the'usual commercial grades will produce inferior castingswhich lose many of the desired characteristics of the alloy producedaccording to my invention because of the impurities which aluminumcontain. Also, I have found that too much copper will so reduce thecapillary action as to make the metal sluggish in the mold; and that toomuch silicon will make the castings too brittle for uses where wear andcorrosion resistance is most desirable. I have found too that a greaterquantity of magnesium than that sp cified above will result in aproportionate decrease of corrosion resistance under both acid andalkaline conditions. The stated proportions of silver and nickel havebeen found to be just enough to produce good solid castings of optimumquality and a greater quantity of these materials than that specifiedwould merely be a Waste.

An optimum formula for my improved alloy is as folice lows, theproportions being in percentages of the total melt:

Percent Beryllium 0.06 Copper 1.65 Silicon 0.12 Nickel 0.44 Silver 0.25

Magnesium 1.11 Titanium 0.16 Aluminum Balance When making the improvedalloy the pure aluminum should be melted down to a liquid state at atemperature of about 1450 F. This heat should never exceed 1530 F. sothat oxidation of the aluminum will be minimized. The presence of theoxide will show on the surface of the casting and also is detrimental totensile strength. When the aluminum is melted the alloying materials arethen added, and when the entire batch is molten it is ready to be pouredin a normal casting procedure.

A typical melt of small size may be made as follows:

To pounds of pure virgin aluminum, melted down to liquid state at 1450F. add 16 ounces of beryllium copper containing 2 /Zt% beryllium, 8ounces of silicon cop per containing 25% silicon, 10 ounces of titaniumaluminimum containing 25% titanium, 30 ounces of nickel aluminumcontaining 25 nickel, 4 ounces of silver, and 15 ounces of magnesium.

From the foregoing it will be seen that the source of beryllium andsilicon is also the source of the copper for the improved alloy. Thetitanium aluminum compound is used as a titanium source to obviate theentry of iron into the alloy; and the nickel aluminum compound is usedbecause of its lower melting point than that of pure nickel. The size ofthe melt may be varied to substantially any desired extent by merelyvarying proportionately the above stated quantities of the severalingredients.

Castings made from this alloy, when allowed to naturally age for aperiod of ten to twenty days, according to the weight and size of thecast product, are found to have all of the desired characteristics whichwere the objectives sought in the course of my development of thepresent invention, including complete stability against dimensionalchange. Additionally these castings exhibit a very high salt resistanceand a remarkably high resistance to abrasion and wear. Other physicalproperties of my new aluminum alloy are as follows:

Tensile strength (minimum) p.s.i 28,433 Corrosion test at pH 7 hours 72Density gm./cc 2.73 Hardness (500 kg. load) B.H.N 69 Pouring temperature(preferred pouring temp.

is about 1260 F.) 1250-1350 Solidification range of density F 1160-1015My improved aluminum alloy is particularly useful for pistons and pumpimpellers, particularly for impellers of pumps in sewage disposalplants, steel mills, and similar places where the pumpage is highabrasive or highly acid. For such uses impellers of my improved alloyhave outlasted impellers made of manganese steel, and operating underidentical conditions, by more than four times the life of the lattermaterial. Other uses for which my improved alloy has been found to beexceptionally well suited as in various marine applications where highresistance to salt water corrosion is a necessity. My new aluminum alloyhas the additional advantages of excellent machineability and goodimpact strength as well as the fact that it has and retains a brightwhite color.

Having thus described my invention what is claimed as new and desired tobe secured by Letters Patent is defined as follows:

I claim:

1. An alloy consisting of about 0.05% to about 0.08% by weightberyllium, about 1.60% to about 1.68% by Weight copper, about 0.10% toabout 0.18% by Weight silicon, about 0.42% to about 0.48% by weightnickel, about 0.20% to about 0.30% by weight silver, about 1.10% toabout 1.18% by weight magnesium, about 0.15% to about 0.19% by weighttitanium, and the balance being aluminum.

2. An aluminum alloy according to claim 1 consisting of the followingmaterials:

Percent by weight Beryllium 0.05-0.08 Copper 1.60-1.68 Silicon 0.10-0.18Nickel 0.42-0.48 Silver -0.20-0.30 Magnesium 1.10-1.18 Titanium0.15-0.19

Aluminum (virgin) Balance 3. An alloy according to claim 1 wherein thecomponents are in the following proportions by weight: 0.06% beryllium,1.65% copper, 0.12% silicon, 0.44% nickel, 0.25% silver, 1.11%magnesium, 0.16% titanium, and the balance is substantially purealuminum.

4. An alloy according to claim 1 wherein the ingredients are in thefollowing proportions: beryllium, 0.06%; copper, 1.65%; silicon, 0.12%;nickel, from about 0.42% to 0.48%; silver from about 0.20% to about0.30%; magnesium, 1.11%; titanium, 0.16%; and the balance issubstantially pure aluminum.

References Cited UNITED STATES PATENTS 2,383,026 8/1945 Toleik 75-1422,522,575 9/1950 Hall et a1. 75142 3,172,790 3/1965 Gilmore et al.75-142 3,288,601 11/1966 Flemings et a1. 75-142 HYLAND BIZOT, PrimaryExaminer.

RICHARD O. DEAN, Examiner.

1. AN ALLOY CONSISTING OF ABOUT 0.05% TO ABOUT 0.08% BY WEIGHTBERYLLIUM, ABOUT 1.60% TO ABOUT 1.68% BY WEIGHT COPPER, ABOUT 0.10% TOABOUT 0.18% BY WEIGHT SILICON, ABOUT 0.42% TO ABOUT 0.48% BY WEIGHTNICKEL, ABOUT 0.20% TO ABOUT 0.30% BY WEIGHT SILVER, ABOUT 1.10% TOABOUT 1.18% BY WEIGHT MAGNESIUM, ABOUT 0.15% TO ABOUT 0.19% BY WEIGHTTITANIUM, AND THE BALANCE BEING ALUMINUM.